<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>demo01</title>
  <script src="../lib/react.js"></script>
  <script src="../lib/react-dom.js"></script>
  <script src="../lib/browser.js"></script>
</head>
<body>
<div id="root"></div> 

<script type="text/babel">
/* 相当于
const element = React.createElement(
  'h1',
  {className: 'greeting'},
  'Hello, world!'
);
*/ 
const element = <h1 className="greeting">Hello, world! </h1>
ReactDOM.render(
  element,
  document.getElementById('root')
);
</script>
</body>
</html>